Rubbery polymer with improved properties

ABSTRACT

The present invention discloses a rubbery polymer having improved properties, which is comprised of an inner core and an outer shell, wherein the inner core is comprised of a polymeric structure having repeat units which are derived from (a) butyl acrylate, (b) a member selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate, and ethyl acrylate, (c) optionally, an alkoxy ethyl acrylate or an alkoxy ethyl methacrylate, (d) acrylonitrile, (f) a cross-linking agent, and (g) a monomer containing reactive cure sites, wherein the outer core is comprised of a polymeric structure having repeat units which are derived from (d) acrylonitrile, (e) styrene, and (f) additional cross-linking agent, wherein the outer core is void of repeat units which are derived from methyl methacrylate.

This is a continuation-in-part application of U.S. patent applicationSer. No. 11/145,402, filed on Jun. 3, 2005, which is a divisional ofU.S. patent application Ser. No. 10/740,250, filed on Dec. 18, 2003 (nowissued as U.S. Pat. No. 6,984,686).

BACKGROUND OF THE INVENTION

Automotive instrument panels and door panels are typically compositeswhich are made of a rigid backing which supports a semi-rigid urethanefoam with the semi-rigid urethane foam being covered with a skincompound. Such skin compounds are typically blends of polyvinyl chloride(PVC) with a nitrile rubber (NBR). The nitrile rubber is included insuch blends as a permanent modifier for the PVC which provides it with ahigher degree of flexibility.

The automotive industry is currently moving toward more aerodynamic bodydesigns which typically include larger glass areas. Such design changeshave significantly increased the heat and ultraviolet light agingrequirements of automotive interiors. This has in turn significantlyincreased the demands put upon the polymers which are utilized as skinsin automotive interior panels.

Heat and light stabilizers can be employed to improve the heat andultraviolet light aging characteristics of conventional PVC/NBR blendswhich are utilized as skins for automotive interior panels.

However, the degree to which the aging characteristics of such blendscan be improved by the addition of additives is limited. In fact, thereis a demand for performance characteristics in such applications whichtheretofore has not been realized by the utilization of heat and lightstabilizers. For instance, it would be highly desirable for the skinsused in automotive panels to resist discoloration and cracking underconditions of high heat and intense ultraviolet light throughout thelife of the vehicle.

NBR/PVC blends offer an array of physical properties which make themuseful as a skin composition for automotive panels. The NBR acts as apermanent flexibilizing polymer for the PVC. It also acts as a shrinkagecontrol agent and embossing aid and improves grain retention. The NBR insuch blends further provides vacuum forming gauge control and exhibitslow fog characteristics. NBR is highly compatible with PVC and has thecapability of being recycled. It is essential for any polymer which issubstituted for NBR to display these essential characteristics.

U.S. Pat. No. 5,380,785, U.S. Pat. No. 5,415,940, U.S. Pat. No.5,504,155, U.S. Pat. No. 5,504,160 and U.S. Pat. No. 5,616,651 disclosea rubbery polymer which can be blended with PVC to make leatherycompositions. These compositions are particularly useful inmanufacturing skins for automotive interior paneling. Skin compositionswhich are made utilizing this rubbery polymer provide a higher level ofresistance to heat and ultraviolet light than those made utilizingconventional NBR/PVC blends. The rubbery polymers of U.S. Pat. No.5,380,785 also offer low fog characteristics; low odor, shrinkagecontrol, and grain retention. They also act as an embossing aid and as apermanent flexibilizing modifier. These rubbery polymers also havecharacteristics which make them useful in building gasket applications.

U.S. Pat. No. 5,380,785 also specifically discloses a rubbery polymerwhich can be blended with polyvinyl chloride to make leatherycompositions having good heat and ultraviolet light resistance, saidrubbery polymer being comprised of repeat units which are comprised of(a) butyl acrylate, or optionally a mixture of butyl acrylate and2-ethylhexyl acrylate containing up to about 40% 2-ethylhexyl acrylate,(b) at least one member selected from the group consisting of methylmethacrylate, ethyl methacrylate, methyl acrylate, and ethyl acrylate,(c) acrylonitrile, (d) styrene, (e) a half ester maleate soap, and (f) acrosslinking agent. Polymers of this general type are sold by Eliokem asSunigum® rubber.

U.S. Pat. No. 5,962,591 discloses that blends of certain rubberypolymers with polyolefins can be compatibilized with ethylene alkylacrylates or ethylene vinyl acetate. These blends can be made so as tobe useful as skins for automotive interior panels and can be made so asto be leathery in nature.

SUMMARY OF THE INVENTION

The present invention relates to a rubbery polymer which can be blendedwith polyvinylchloride (PVC), halogen containing polymers,polyurethanes, styrenic polymers (polymers which contain styrene such asacrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate(ASA), styrene ethylene butadiene styrene (SEBS), etc.), polyesters andcopolymers ester-ether (COPE), polyamides, polycarbonates, as well aspolyolefins via compatibilization techniques to make leatherycompositions.

The compositions according to the invention are particularly useful inmanufacturing skins for automotive interior paneling. Skin compositionswhich are made utilizing this rubbery polymer provide a higher level ofresistance to heat and ultraviolet light than those made utilizingconventional NBR/PVC blends. The rubbery polymers of this invention alsooffer low fog characteristics, low odor, shrinkage control, and grainretention. They also act as an embossing aid and as a permanentflexibilizing modifier. The rubbery polymers of this invention also havecharacteristics which made them useful in building gasket applications.

The present invention more specifically discloses a rubbery polymerhaving improved properties, which is comprised of repeat units which arecomprised of (a) butyl acrylate, or optionally a mixture of butylacrylate and 2-ethylhexyl acrylate containing up to about 40 percent2-ethylhexyl acrylate, (b) at least one member selected from the groupconsisting of methyl methacrylate, ethyl methacrylate, methyl acrylate,and ethyl acrylate, (c) optionally, about 0% to about 40% of an alkoxyethyl acrylate or an alkoxy ethyl methacrylate, (d) acrylonitrile, (e)styrene, and (f) a crosslinking agent; wherein about 1% to about 10% ofa monomer containing reactive cure sites selected from the groupconsisting of hydroxyl groups, glycidyl groups, carboxylic acid groups,and unsaturated cure sites is incorporated into the rubbery polymer.

The present invention further discloses a process for preparing arubbery polymer which can be blended with thermoplastics to makeleathery compositions having good heat and ultraviolet light resistance,said process comprising the steps of (1) polymerizing (a) butylacrylate, or optionally a mixture of butyl acrylate and 2-ethylhexylacrylate containing up to about 40% 2-ethylhexyl acrylate, (b) at leastone member selected from the group consisting of methyl methacrylate,ethyl methacrylate, methyl acrylate, and ethyl acrylate, (c) optionallyabout 0% to about 40% of alkoxy ethyl me(acrylate), (d) acrylonitrile,and (e) a crosslinking agent; wherein about 1% to about 10% of a monomercontaining reactive cure sites selected from the group consisting ofhydroxyl groups, glycidyl groups, carboxylic acid groups, andunsaturated cure sites is incorporated into the rubbery polymer underemulsion polymerization conditions to produce a seed polymer containinglatex; (2) adding (a) styrene, (b) additional acrylonitrile, and (c)additional crosslinking agent to the seed polymer containing latex underemulsion polymerization conditions which result in the formation of anemulsion containing the rubbery polymer; (3) recovering the rubberypolymer from the emulsion containing the rubbery polymer.

DETAILED DESCRIPTION OF THE INVENTION

The present invention discloses a rubbery polymer which can be blendedwith PVC, halogen containing polymers, polyurethanes, styrenic polymers(polymers which contain styrene such as ABS, ASA, SEBS, etc.),polyesters and copolymers ester-ether (COPE), polyamides,polycarbonates, as well as polyolefins via compatibilization techniquesto make leathery compositions having good heat and ultraviolet lightresistance, said rubbery polymer being comprised of repeat units whichare comprised of (a) butyl acrylate, or optionally a mixture of butylacrylate and 2-ethylhexyl acrylate containing up to about 40%2-ethylhexyl acrylate, (b) at least one member selected from the groupconsisting of methyl methacrylate, ethyl methacrylate, methyl acrylate,and ethyl acrylate, (c) optionally, about 0 to about 40% of alkoxy ethylme(acrylate), (d) acrylonitrile, (e) styrene, and (f) a crosslinkingagent; wherein about 1 to about 10% of a reactive cure site (co)monomercontaining hydroxyl groups, glycidyl groups, carboxylic acid groups, orunsaturated cure site is incorporated during emulsion polymerizationonto said rubbery polymer.

Advantageously, such rubbery polymers contain repeat units (chainlinkages) which are derived from (a) butyl acrylate, or optionally amixture of butyl acrylate and 2-ethylhexyl acrylate containing up toabout 40% 2-ethylhexyl acrylate, (b) at least one member selected fromthe group consisting of methyl methacrylate, ethyl methacrylate, methylacrylate, and ethyl acrylate, (c) optionally, about 0 to about 40% ofalkoxy ethyl me(acrylate), (d) acrylonitrile, (e) styrene, and (f) acrosslinking agent; wherein (g) about 1 to about 10% of a reactive curesite (co)monomer containing hydroxyl groups, glycidyl groups, carboxylicacid groups, or unsaturated cure site is incorporated during emulsionpolymerization onto said rubbery polymer.

These repeat units differ from the monomers that they were derived fromin that they contain one less carbon-carbon double bond than is presentin the respective monomer. In other words, a carbon-to-carbon doublebond is consumed during the polymerization of the monomer into a repeatunit in the rubbery polymer. Thus, in saying that the rubbery polymercontains various monomers in actuality means that it contains repeatunits which are derived from those monomers.

The rubbery polymers, which are modified in accordance with thisinvention, will normally contain (a) from about 40 to about 80% byweight butyl acrylate, or optionally a mixture of butyl acrylate and2-ethylhexyl acrylate containing up to 40% by weight 2-ethylhexylacrylate, (b) from about 5 to about 35% by weight methyl methacrylate,ethyl methacrylate, methyl acrylate, or ethyl acrylate, (c) optionallyabout 0 to about 40% of alkoxy ethyl me(acrylate), (d) from about 4 toabout 30% by weight acrylonitrile, (e) from about 3 to about 25% byweight styrene, (f) from about 0.25 to about 8% by weight of acrosslinking agent wherein (g) from about 0.1 to about 10% by weight ofa reactive cure site (co)monomer containing hydroxyl groups, glycidylgroups, carboxylic acid groups, or unsaturated cure site is incorporatedduring emulsion polymerization onto said rubbery polymer.

Such rubbery polymers will preferably contain (a) from about 50 to about80% by weight butyl acrylate, or optionally a mixture of butyl acrylateand 2-ethylhexyl acrylate containing up to about 40% 2-ethylhexylacrylate, (b) from about 3 to about 25% by weight of at least one memberselected from the group consisting of methyl methacrylate, ethylmethacrylate, methyl acrylate, and ethyl acrylate, (c) optionally, about0 to about 40% of alkoxy ethyl me(acrylate), (d) from about 6 to about30% by weight acrylonitrile, (e) from about 5 to about 18% by weightstyrene, (f) from about 0.5 to about 4% by weight of a crosslinkingagent wherein (g) from about 1 to about 8% by weight of a reactive curesite (co)monomer containing hydroxyl groups, glycidyl groups, carboxylicacid groups, or unsaturated cure site is incorporated during emulsionpolymerization onto said rubbery polymer.

The rubbery polymer will more preferably be comprised of repeat unitswhich are derived from (a) from about 55 to about 75% by weight butylacrylate, or optionally a mixture of butyl acrylate and 2-ethylhexylacrylate containing up to about 40% 2-ethylhexyl acrylate, (b) fromabout 5 to about 20% by weight of at least one member selected from thegroup consisting of methyl methacrylate, ethyl methacrylate, methylacrylate, and ethyl acrylate, (c) optionally about 0 to about 40% ofalkoxy ethyl me(acrylate), (d) from about 10 to about 25% by weightacrylonitrile, (e) from about 8 to about 14% by weight styrene, (f) fromabout 1 to about 3% by weight of a crosslinking agent wherein (g) fromabout 2 to about 6% by weight of a reactive cure site (co)monomercontaining hydroxyl groups, glycidyl groups, carboxylic acid groups, orunsaturated cure site is incorporated during emulsion polymerizationonto said rubbery polymer. These percentages are based upon the totalweight of the rubbery polymer.

A variety of reactive cure site (co)monomers can be used in carrying outthe polymerizations to produce the rubbery polymer. These monomerscontain reactive cure sites which are selected from the group consistingof hydroxyl groups, glycidyl groups, carboxyl groups, and unsaturatedcure sites.

Some representative examples of monomers containing reactive cure siteswhich can be utilized include carboxyl derivatives such as acrylic ormethacrylic acid, maleic acid, fumaric acid and itaconic acid; hydroxyderivatives such as 2-hydroxyethyl (me)acrylate, 2-hydroxypropyl(me)acrylate, 3-hydroxypropyl (me)acrylate, 2-hydroxyethyl crotonate,pentahydroxyethyl (me)acrylate, 2,3,4,5-tetrahydroxy-pentyl(me)acrylate, etc. The particularly preferable monomers are acrylicacid, methacrylic acid, 2-hydroxyethyl acrylate, and hydroxyethylmethacrylate.

Some representative examples of glycidyl derivatives which can beutilized include glycidyl (me)acrylate, allyl glycidyl ether, itaconicacid monoglycidyl ester, butenetricarboxylic acid monoglycidyl ester,butenetricarboxylic acid diglycidyl ester, butenetricarboxylic acidtriglycidyl ester, vinyl glycidyl ethers and esters of maleic acid,fumaric acid and crotonic acid, etc. The particularly preferablemonomers are glycidyl (me)acrylate and allyl glycidyl ether.

Some representative examples of monomers containing unsaturated curesites can be utilized include 1,3-butadiene, isoprene, allyl maleate,tetrahydrobenzyl acrylate, diallyl phthalate, dicyclopentenyl acrylate,dicyclopentenyloxyethyl methacrylate, and the like. When the reactivecure site is an unsaturated cure site, sulfur vulcanization with orwithout accelerator or other vulcanization agents such as phenoliccuratives, benzoquinone derivatives, metal oxides, organic peroxides andbismaleimides can be used to improve the polymer network duringprocessing as described by A. Y. Coran in Encyclopedia of PolymerScience and Engineering, 17 (Second Edition), 666-698. When the reactivecure sites are carboxy derivatives, hydroxy derivatives or glycidylderivatives, chemical reactions are more preferable to improvecompatiblization or polymer network during processing or polymerblending.

The present invention further reveals a leathery composition that isuseful in automotive applications which is comprised of (1) athermoplastic such as PVC, halogen containing polymers, polyurethanes,styrenic polymers (polymers which contain styrene such as ABS, ASA,SEBS, etc.), polyesters and copolymers ester-ether (COPE), polyamides,polycarbonates, as well as polyolefins via compatibilization techniques,(2) a plasticizer, and (3) a rubbery polymer which is comprised of (a)butyl acrylate, or optionally a mixture of butyl acrylate and2-ethylhexyl acrylate containing up to about 40 percent 2-ethylhexylacrylate, (b) at least one member selected from the group consisting ofmethyl methacrylate, ethyl methacrylate, methyl acrylate, and ethylacrylate, (c) optionally, about 0 to about 40% of alkoxy ethylme(acrylate), (d) acrylonitrile, (e) styrene, and (f) a crosslinkingagent; wherein about 1 to about 10% of a reactive cure site (co)monomercontaining hydroxyl groups, glycidyl groups, carboxylic acid groups, orunsaturated cure site is incorporated during emulsion polymerizationonto said rubbery polymer.

These leathery compositions offer an excellent combination of propertiesfor utilization in making skin compounds for panels used in automotiveapplications. These leathery compositions can be prepared by blendingthe rubbery polymer into polyvinylchloride (PVC) utilizing standardmixing techniques. It is highly preferred for the improved rubberypolymer of this invention to be in powdered form when blended into PVCto make such leathery compositions. A wide variety of plasticizers whichare compatible with the polyvinyl chloride resins can be employed.

Such leathery compositions typically contain from about 40 to 160 partsby weight of the improved rubbery polymer of this invention, from about10 to about 50 parts of a plasticizer, and from about 0.1 to about 5parts by weight of an antidegradant per 100 parts by weight of thepolyvinylchloride. It is typically preferred for such leatherycompositions to contain from about 60 to about 120 parts by weight ofthe improved rubbery polymer of this invention, from about 15 to about40 parts of the plasticizer, and from about 0.5 to 3 parts of anantidegradant (per 100 parts of the PVC). It is typically more preferredfor the leathery composition to contain from about 70 to about 90 partsby weight of the improved rubbery polymer of this invention, from about20 to about 30 parts by weight of the plasticizer, and from about 1 to 2parts by weight of the antidegradant per 100 parts by weight of the PVC.Such compositions will also generally contain anacrylonitrile-butadiene-styrene resin (ABS resin).

The leathery composition will typically contain from about 15 parts toabout 80 parts of ABS resin per 100 parts of PVC. The leatherycomposition will preferably contain from about 25 to about 55 parts perweight of the ABS resin per 100 parts by weight of the PVC. It isgenerally more preferred for the leathery composition to contain fromabout 30 to about 40 parts by weight of the ABS resin per 100 parts byweight of PVC. Various colorants and/or pigments will typically also beadded to the composition to attain a desired color.

The leathery compositions of this invention are useful in a wide varietyof applications. For example, they have been found to be extremelyvaluable when used in making skins for automotive panels. Such panelsare typically comprised of a semi-rigid urethane foam which is supportedby a rigid backing and covered with the leathery composition of thisinvention. Such skins are made by calendaring the leathery compositionsof this invention and then cutting them to the desired size and shape.Such skins for automotive applications which are made with the leatherycompositions of this invention offer outstanding heat and ultravioletlight stability. These are highly desirable characteristics which canhelp to prevent the skin of automotive panels from cracking during thenormal life of the vehicle.

The improved rubbery polymers of this invention can also be blended withother halogen containing polymers (in addition to PVC), styrenicpolymers (polymers which contain styrene, such asacrylonitrile-styrene-acrylate (ASA) polymers, ABS, SEBS polymers,etc.), polyesters and copolyester-ether, polycarbonates, polyamides,polyurethanes, polyolefins to produce compositions which exhibit goodheat and ultraviolet light resistance. Such polymeric compositions canbe used in manufacturing a wide variety of useful articles, such asprofiles, moldings, sheeting, flooring, wall coverings, hose, cables,and footwear. Virtually any type of polyamide (nylon) can be utilized inpreparing such blends. These nylons are generally prepared by reactingdiamines with dicarboxylic acids. The diamines and dicarboxylic acidswhich are utilized in preparing such nylons will generally contain fromabout 2 to about 12 carbon atoms. However, nylons which can be utilizedin such blends can also be prepared by addition polymerization. Somerepresentative examples of nylons which can be used include nylon-6,6,nylon-6, nylon-7, nylon-8, nylon-9, nylon-10, nylon-11, nylon-12 andnylon-6,12. Some representative examples of polyolefins which can beused include low density polyethylene, linear low density polyethylene,high density polyethylene, polypropylene, metallocene catalyzedpolyolefins, and modified polyolefins, such as ethylene vinyl acetate(EVA), ethylene-alkyl (me)acrylate or terpolymers of ethylene, alkyl(me)acrylate and acrylic acid.

The present invention further discloses a process for preparing arubbery polymer which can be blended with PVC, halogen containingpolymers, polyurethanes, styrenic polymers (polymers which containstyrene such as ABS, ASA, SEBS, etc.), polyesters and copolymersester-ether (COPE), polyamides, polycarbonates, as well as polyolefinsvia compatibilization techniques to make leathery compositions havinggood heat and ultraviolet light resistance, said process comprising thesteps of (1) polymerizing (a) butyl acrylate, or optionally a mixture ofbutyl acrylate and 2-ethylhexyl acrylate containing up to about 40%2-ethylhexyl acrylate, (b) at least one member selected from the groupconsisting of methyl methacrylate, ethyl methacrylate, methyl acrylate,and ethyl acrylate, (c) optionally, about 0 to about 40% of alkoxy ethylme(acrylate), (d) acrylonitrile, and (e) a crosslinking agent; whereinabout 1 to about 10% of a reactive cure site (co)monomer containinghydroxyl groups, glycidyl groups, carboxylic acid groups, or unsaturatedcure site is incorporated under emulsion polymerization conditions toproduce a seed polymer containing latex; (2) adding (a) styrene, (b)additional acrylonitrile, and (c) additional crosslinking agent to theseed polymer containing latex under emulsion polymerization conditionswhich result in the formation of an emulsion containing the rubberypolymer; (3) recovering the rubbery polymer from the emulsion containingthe rubbery polymer.

The rubbery polymers which are modified in accordance with the processof the present invention are synthesized in an aqueous reaction mixtureby utilizing a free radical polymerization technique. The reactionmixture utilized in this polymerization technique is comprised of water,the appropriate monomers, a suitable free radical initiator, acrosslinking agent, and a soap.

A wide variety of soaps (emulsifiers) can be utilized in carrying outthe polymerization to produce the rubbery polymer. Some representativeexamples of soaps which can be utilized include the half ester maleatesoap, and/or the metal salt of an alkyl sulfonate or the metal salt ofan alkyl sulfate.

The half ester maleate soap utilized in the polymerization is preparedby reacting maleic anhydride with a fatty alcohol containing from about10 to about 24 carbon atoms. It is typically preferred to utilize afatty alcohol which contains from about 12 to about 16 carbon atoms. Onemole of the maleic anhydride is reacted with one mole of the fattyalcohol in producing the half ester maleate soap. This reaction istypically conducted at a temperature that is within the range of about50° C. to about 80° C. Sodium hydroxide or potassium hydroxide is thenadded to make the half ester maleate soap.

Some representative examples of sulfonate and sulfate surfactants whichcan be used include sodium toluene-xylene sulfonate, sodium toluenesulfonate, sodium cumene sulfonate, sodium decyldiphenyl ethersulfonate, sodium dodecylbenzenesulfonate, sodium dodecyldiphenylethersulfonate, sodium 1-octane sulfonate, sodium tetradecane sulfonate,sodium pentadecane sulfonate, sodium heptadecane sulfonate. Metal saltsof alkylbenzene sulfonates are a highly preferred class of sulfonatesurfactant. The metal will generally be sodium or potassium.

The sulfonate surfactant can be a mixture of (mono)dialkylate etherdisulfonates. The advantage of the disulfonate structure is that itcontains two ionic charges per molecule instead of one as in the casewith conventional alkyl sulfonate surfactants.

The sulfate surfactants, which are useful in the practice of thisinvention, include metal salts of alkylsulfates having the structuralformula ROSO₃X and metal salts of alkylethersulfates having thestructural formula RO(CH₂CH₂O)_(n)SO₃X, wherein R represents an alkylgroup and wherein X represents sodium or potassium. Sodium laurylsulfate, sodium ethanolamine lauryl sulfate, triethanolamine laurylsulfate are representative examples of commercially available sulfatesurfactants.

The reaction mixture utilized in this polymerization technique willnormally contain from about 10 to about 80% by weight monomers, basedupon the total weight of the reaction mixture. The reaction mixture willpreferably contain from about 20 to about 70% by weight monomers andwill more preferably contain from about 40 to about 50% by weightmonomers.

The free radical emulsion polymerizations utilized in synthesizing therubbery polymer are typically conducted at a temperature which is withinthe range of about 10° C. to about 95° C. In most cases, thepolymerization temperature utilized will vary between about 20° C. andabout 80° C. The polymerization is carried out as a two-step batchprocess. In the first step, a seed polymer containing latex issynthesized.

This is done by polymerizing (a) butyl acrylate, or optionally a mixtureof butyl acrylate and 2-ethylhexyl acrylate containing up to about 40%2-ethylhexyl acrylate, (b) at least one member selected from the groupconsisting of methyl methacrylate, ethyl methacrylate, methyl acrylate,and ethyl acrylate, (c) optionally, about 0 to about 40% of alkoxy ethylme(acrylate), (d) acrylonitrile, (e) a crosslinking agent wherein (f)about 1 to about 10% of a reactive cure site (co)monomer containinghydroxyl groups, glycidyl groups, carboxylic acid groups, or unsaturatedcure site is incorporated during emulsion polymerization onto saidrubbery polymer.

The seed polymer containing latex is typically prepared by thepolymerization of a monomer mixture which contains about 40 to about 90%by weight butyl acrylate, or optionally, a mixture of butyl acrylate and2-ethylhexyl acrylate containing up to about 40% 2-ethylhexyl acrylate,from about 5 to about 35% by weight methyl methacrylate, ethylmethacrylate, methyl acrylate, or ethyl acrylate, from about 2 to about30% by weight acrylonitrile, and from about 0.25 to 6% by weight of thecrosslinking agent wherein from about 0.1 to about 10% by weight of a(co)monomer containing hydroxyl groups, glycidyl groups, carboxylic acidgroups, or unsaturated cure site is incorporated during emulsionpolymerization onto said rubbery polymer.

It is typically preferred for the monomeric component utilized in thefirst step to include about 50 to about 85% by weight butyl acrylate, oroptionally a mixture of butyl acrylate and 2-ethylhexyl acrylatecontaining up to about 40% 2-ethylhexyl acrylate, from about 5 to about30% by weight ethyl acrylate, ethyl methacrylate, methyl acrylate, ormethyl methacrylate, from about 4 to about 28% by weight acrylonitrile,and from about 0.5 to about 4% by weight of the crosslinking agentwherein (g) from about 0.1 to about 10% by weight of a (co)monomercontaining hydroxyl groups, glycidyl groups, carboxylic acid groups, orunsaturated cure site is incorporated during emulsion polymerizationonto said rubbery polymer.

It is generally more preferred for the monomer charge composition usedin synthesizing the seed polymer latex to contain from about 60% toabout 80% by weight butyl acrylate, or optionally a mixture of butylacrylate and 2-ethylhexyl acrylate containing up to about 40%2-ethylhexyl acrylate, from about 5 to about 25% by weight methylmethacrylate, ethyl methacrylate, methyl acrylate, or ethyl acrylate,from about 5 to about 25% by weight acrylonitrile, and from about 1 toabout 3% by weight crosslinking agent wherein (g) from about 0.1 toabout 10% by weight of a (co)monomer containing hydroxyl groups,glycidyl groups, carboxylic acid groups, or unsaturated cure site isincorporated during emulsion polymerization onto said rubbery polymer.

After the seed polymer latex has been prepared, styrene monomer,additional acrylonitrile monomer, and additional crosslinking agent isadded to the seed polymer containing latex. As a general rule, fromabout 4 parts by weight to about 30 parts by weight of styrene, fromabout 1 part by weight to about 20 parts by weight of additionalacrylonitrile, and from about 0.01 to 2 parts by weight of thecrosslinking agent will be added to the seed polymer per 100 parts dryweight of the seed polymer. In this second stage of the polymerization,it is preferred to add from about 6 parts by weight to about 22 parts byweight of styrene, from about 3 parts by weight to about 12 parts byweight of acrylonitrile, and from about 0.05 parts by weight to 1 partby weight of the crosslinking agent. It is typically more preferred forfrom about 10 parts by weight to about 17 parts by weight of styrene,from about 4 parts by weight to about 8 parts by weight ofacrylonitrile, and from about 0.1 parts by weight to about 0.5 parts byweight of the crosslinking agent to be added to the seed polymer latexto initiate the second phase of the polymerization.

A wide variety of crosslinking agents can be utilized in carrying outthe polymerizations to produce the rubbery polymer. Some representativeexamples of crosslinking agents which can be utilized includedifunctional acrylates, difunctional methacrylates, trifunctionalacrylates, trifunctional methacrylates, and divinylbenzene.1,4-butanediol dimethacrylate has proven to be particularly useful asthe crosslinking agent.

The rubbery polymer can be made by the two-step batch, semi-continuous,or continuous emulsion polymerization process. In most cases, thepolymerization will be continued until a high monomer conversion hasbeen reached. At this point, the rubbery polymer made by the two-steppolymerization process is recovered from the emulsion (latex) after theoptional deodorizing step. This can be accomplished by utilizingstandard coagulation techniques. For instance, coagulation can beaccomplished by the addition of salts, acids, or both to the latex.

After the rubbery polymer is recovered by coagulation, it can be washedto further reduce odors. This can be accomplished by simply pouring orspraying water on the rubbery polymer. The rubbery polymer can also bewashed by putting it in a water bath which will further reduce odor.After being washed, the rubbery polymer is generally dried. It issometimes advantageous to convert the rubbery polymer into a powder tofacilitate its usage. In this case, it will be beneficial to add apartitioning agent to the rubbery polymer. Some representative examplesof partitioning agents which can be employed include calcium carbonate,emulsion polyvinyl chloride, and silica. Calcium carbonate is a highlydesirable partitioning agent which can be utilized in such applications.

The rubbery polymers made by the process of this invention are comprisedof an inner core and an outer shell. The inner core is comprised of apolymeric structure having repeat units which are derived from (a) butylacrylate, (b) a member selected from the group consisting of methylmethacrylate, ethyl methacrylate, methyl acrylate, and ethyl acrylate,(c) optionally, an alkoxy ethyl acrylate or an alkoxy ethylmethacrylate, (d) acrylonitrile, (f) the cross-linking agent, and (g)the monomer containing reactive cure sites are polymerized in the firstpolymerization step. The outer core is comprised of a polymericstructure having repeat units which are derived from (d) acrylonitrile,styrene, and the cross-linking agent. The outer core is void of repeatunits which are derived from methyl methacrylate.

This invention is illustrated by the following examples that are merelyfor the purpose of illustration and are not to be regarded as limitingthe scope of the invention or the manner in which it can be practiced.Unless specifically indicated otherwise, parts and percentages are givenby weight.

EXAMPLE 1 Comparative Example

In this experiment, a rubbery polymer was made in a 10 liter stainlesssteel reactor. The reactor was equipped with an axially flow turbineagitator which was operated at 450 rpm (revolutions per minute). Thereactor was charged with 6348.68 grams of water, 72.8 grams of a halfester maleate soap (made with a C₁₆ fatty alcohol), 2.73 grams of sodiumdodecylbenzenesulfonate, 31.2 grams of a 50 percent aqueous potassiumhydroxide solution, 5.2 grams of sodium pyrophosphate, 1837.68 grams ofn-butylacrylate, 218.4 grams of acrylonitrile, 109.2 grams ofmethylmethacrylate, 44.2 grams of 1,4-butanediol dimethacrylate, 2.08grams of t-dodecylmercaptan, 1.56 grams of triethanol amine, and 6.5grams of potassium persulfate were initially charged into the reactor. Atemperature of about 35° C. was maintained during the first stage of thepolymerization. When a solids content of about 20% was reached thereaction temperature was increased to about 60° C. and a temperature ofabout 60° C. was maintained throughout the polymerization until thetotal solids content of about 25% was achieved. This first stage ofpolymerization was carried out for a period of about 2.5 hours. Thisfirst stage polymerization resulted in the production of seed polymerlatex which was used in the second step of the polymerization.

In the second step of the polymerization, 124.8 grams of acrylonitrile,242 grams of styrene, 4.68 grams of divinylbenzene, and 0.78 grams oft-dodecylmercaptan were charged into the reactor containing the seedpolymer latex. The polymerization proceeded until a solids content ofabout 30% was reached. The latex made was subsequently coagulated and adry rubber was recovered.

EXAMPLE 2

In this experiment, a rubbery polymer was synthesized in a 10 litresreactor utilizing the technique of this invention. In the procedureemployed 6348.68 grams of water, 72.8 grams of hexadecylmonomaleate, 9.1grams of a 30% solution of sodium dodecylbenzene sulfonate, 31.2 gramsof a 50% aqueous potassium hydroxide solution, 5.2 grams of sodiumpyrophosphate, 8.4 grams of acrylonitrile, 4.2 grams of methylmethacrylate, 71.4 grams of n-butyl acrylate, 39 grams of glycidylmethacrylate, 26 grams of 1,4-butanediol dimethacrylate, 2.08 grams oft-dodecylmercaptan, 1.56 grams of triethanol amine, and 6.5 grams ofpotassium persulfate were initially charged into the reactor. Atemperature of about 35° C. was maintained during the first stage of thepolymerization. When a solids content of about 20% was reached thereaction temperature was increased to about 60° C. and 124.8 grams ofadditional acrylonitrile, 242 grams of styrene, 4.88 grams ofdivinylbenzene, and 0.78 grams of t-dodecylmercaptan were charged intothe reactor. After the polymerization was completed, the latex made wascoagulated and a rubber was recovered.

EXAMPLE 3

The procedure used in Example 2 was repeated in this experiment exceptthat 44.2 grams (instead of 26 grams) of 1,4-butanediol dimethacrylatewas charged into the reactor.

EXAMPLE 4

The procedure used in Example 2 was repeated in this experiment, exceptthat 44.2 grams (instead of 26 grams) of 1,4-butanediol dimethacrylateand 130 grams of dicyclopentenyloxyethyl methacrylate (instead of 39grams of glycidyl methacrylate) were charged into the reactor.Antioxidants, such as Wingstay L® or Wingstay K®, in emulsion form or indispersion form can be used to stabilize the rubbery polymer duringdrying and storage. The latex made was subsequently coagulated and a dryrubber was recovered.

EXAMPLE 5

The procedure used in Example 4 was repeated in this experiment, exceptthat 130 grams of diallyl phthalate was used to replace thedicyclopentenyloxyethyl methacrylate.

EXAMPLES 6-9

In these series of experiments, leathery compositions were made byblending the rubbery polymers made in Examples 1 and 3 or other rubberypolymers (Chemigum®) into PVC. In the procedure used, 40 parts of therubbery polymers were blended into 100 parts of the PVC. The blends madealso included 80 parts of DOP and 3 parts of Ba/Zn. The blends were madeby mixing the components in a mill at 180° C. for 6 minutes and thenpressing them into samples at 180° C. The samples made were then testedto determine their physical properties.

The physical properties of the samples made are reported in Table I. Theblend made in Example 6 contained Eliokem Chemigum® P83, the blend ofExample 7 contained Eliokem Chemigum® P35, the blend of Example 8contained the rubber composition of Example 1, and the blend of Example9 contained the rubber composition of Example 3.

As it can be seen in Table I, all the rubbery polymers made in Examples1 and 3 could be made into leathery compositions, which had goodphysical properties compared to the Chemigum® nitrile rubber. TABLE IModulus Compression Shore A Tensile Elonga- 50% 100% set 22 h atExamples Hardness Strength tion MPa MPa 70° C. Example 6 64   13 MPa500% 3.3 5.8 58.2% Example 7 64   9.7 MPa 417% 2.8 4.9 51.4% Example 865 11.8 MPa 352% 2.2 4.5 56.9% Example 9 65 10.9 MPa 326% 2.3 4.5 56.4%

EXAMPLES 10-13

In this series of experiments, leathery compositions were made byblending the rubbery polymers made in Examples 1, 4 and 5 into PVC. Theprocedure of Examples 6-9 was repeated except 100 parts of the rubberypolymers was blended into 100 parts of the PVC.

The physical properties of the samples made are reported in Table II.The blend made in Example 10 contained the rubber composition of Example1, the blend of Example 11 contained rubber composition of Example 4,the blend of Example 12 contained the rubber composition of Example 5,and the blend of Example 13 contained the rubber composition of Example4 and 10 parts of Lotader® AX 8900® per 100 parts of the rubbery polymeras a crosslinking agent. TABLE II Examples 10 11 12 13 Hardness Shore A56 56 57 57 Tensile Strength (MPa) 11.5 10 9.8 10.3 Elongation at break% 282 239 205 232 Modulus at 50% (MPa) 1.8 2.0 2.0 2.2 Modulus at 100%(MPa) 3.5 3.8 3.9 4.2 Tear Strength (kN/m) 23 19.2 19.4 20.6 Compressionset 22 hrs at 70° C. 54.6 48.6 45 42

As it can be seen from Table II, the compression set behavior of theblends made with the rubber composition polymer of this invention wasbetter than was that of the control.

EXAMPLES 14-18

In these series of experiments, rubbery polymer was blended intometallocene catalyzed polyethylene. In the procedure, 60 parts of therubbery polymer was blended at a temperature of 180° C. with 40 parts ofEngage® 8100 in a Haake Rheocord 90 operated at 60 rotations per minuteover a period of 30 minutes. Blends were pressed into samples at 180° C.The samples were then tested to determine their physical properties.

The physical properties of the samples made are reported in Table III.The blend made in Example 14 contained rubber composition of Example 1.Example 15 was a compatibilized blend of the rubber composition ofExample 1 and 10 parts of Lotader® 8900 percent parts of the rubbercomposition polymer. For comparative purposes, a second blend was madewith the rubber composition of Example 3 without including thecompatibilizing polymer in Example 16, or with 10 parts of Lotader® 8900per 100 parts of the rubber composition polymer in Example 17 or with 10parts of Elvax® 360 per 100 parts of the rubber composition in Example18. TABLE III Examples 14 15 16 17 18 Shore A Hardness 60 63 60 63 62Tensile Strength (MPa) 4.3 6.6 4.1 10.4 4.8 Elongation at break (%) 700500 475 490 750 Modulus at 50% (MPa) 1.7 1.9 1.6 1.9 1.8 Modulus at 100%(MPa) 2.6 2.8 2.5 3 2.7 Tear Strength (kN/m) 26 25 24 43 27

As it can be seen from Table III, the physical properties of the blendsmade with the rubber composition polymer of this invention are betterthan those of the control that did not contain any monomers containingglycidyl functional groups.

EXAMPLES 19-25

In this series of experiments, the rubbery polymer was blended into highdensity polyethylene HDPE having a melt flow index (MFI) of about 4. Inthe procedure utilized 70 parts of the rubbery polymer was blended at atemperature of 180° C. with 30 parts of KS10100 high densitypolyethylene (HDPE) from Dow Plastics in a Haake Rheocord 90 operated at60 rpm over a period of 30 minutes. The blends were pressed into samplesat 180° C. The samples were then tested to determine their physicalproperties.

The physical properties of the samples made are reported in Table IV.The blend made in Example 19 contained the rubber composition ofExample 1. Example 20 was a compatibilized a blend of the rubbercomposition of Examples 1 and 10 parts of Elvax® 360, while Example 21was a compatibilized blend of the rubber composition of Example 1 and 10parts of Lotader®AX 8900. For comparative purpose, a second blend wasmade with the rubber composition of Example 2 without including thecompatibilizing polymer in Example 22 or with 10 parts of Elvax® 360 per100 parts of the rubber composition in Example 23. Otherwise, Example 24was the blend of Example 16 including 10 parts of Elvax® 670 and Example25 was the blend of Example 16 including 10 parts of Lotader® AX8900.TABLE IV Examples 19 20 21 22 23 24 25 Tensile at break (MPa) 5.1 5.29.5 5.6 9.8 9.3 12.6 Elongation at break % 74 147 270 71 203 192 282Modulus 50% (MPa) 5.4 5.1 6.4 5.2 6.6 6.5 6.3 Modulus 100% (MPa) — — — —7.9 7.8 7.8 Tear strength kN/m 37 34 54 28 50 44 54

As it can be seen from Table IV, physical properties of compatibilizedblends made with the rubber composition polymer of this invention arebetter than was the control that did not contain any monomers withglycidyl functional groups.

EXAMPLES 26-29

In these series of experiments, the same procedure as utilized inExamples 19-25 was repeated, except 40 parts of the rubbery polymer wasblended with 60 parts of HDPE KS 10100 from Dow Plastics and 10 parts ofthe compatibilizing polymer per 100 parts of the rubber compositionpolymer. Examples 26 and 27 were compatibilized blends of the rubbercomposition of Examples 1 and 2, respectively, and 10 parts of Lotader®AX 8900 per cent parts of the rubber composition polymer. Examples 28and 29 were compatibilized blends of the rubber composition of Examples1 and 2, respectively, and 10 parts of Elvax® 360 per cent parts of therubber composition polymer. The physical properties of the samples madeare reported in Table V. TABLE V Examples 26 27 28 29 Tensile at break(MPa) 8.7 12.6 10.4 12.7 Elongation at break % 287 367 51 184 Modulus50% (MPa) — 12.1 9.7 12.7 Modulus 100% (MPa) — 12 — 12.6 Tear strengthkN/m 113 112 69 80

As it can be seen in Table V, physical properties of the compatibilizedblends made with the rubber composition polymer of this invention arebetter than those of the control for both types of compatibilizingpolymers (Lotader® AX 8900 as well as Elvax® 360).

While certain representative embodiments and details have been shown forthe purpose of illustrating the subject invention, it will be apparentto those skilled in this art that various changes and modifications canbe made therein without departing from the scope of the subjectinvention.

1. A rubbery polymer having improved properties, which is comprised ofan inner core and an outer shell, wherein the inner core is comprised ofa polymeric structure having repeat units which are derived from (a)butyl acrylate, (b) a member selected from the group consisting ofmethyl methacrylate, ethyl methacrylate, methyl acrylate, and ethylacrylate, (c) optionally, an alkoxy ethyl acrylate or an alkoxy ethylmethacrylate, (d) acrylonitrile, (f) a cross-linking agent, and (g) amonomer containing reactive cure sites, wherein the outer core iscomprised of a polymeric structure having repeat units which are derivedfrom (d) acrylonitrile, (e) styrene, and (f) additional cross-linkingagent, wherein the outer core is void of repeat units which are derivedfrom methyl methacrylate.
 2. A rubbery polymer as specified in claim 1which is comprised of repeat units which are derived from (a) about 40to about 80% by weight butyl acrylate, or optionally a mixture of butylacrylate and 2-ethylhexyl acrylate containing up to 40% by weight2-ethylhexyl acrylate, (b) from about 5 to about 35% by weight methylmethacrylate, ethyl methacrylate, methyl acrylate, or ethyl acrylate,(c) optionally, about 0 to about 40% of an alkoxy ethyl acrylate or analkoxy ethyl methacrylate, (d) from about 4 to about 30% by weightacrylonitrile, (e) from about 3 to about 25% by weight styrene, (f) fromabout 0.25 to about 8% by weight of a crosslinking agent, and (g) fromabout 1% to about 10% by weight of the monomer containing reactive curesites.
 3. A rubbery polymer as specified in claim 1 which is comprisedof repeat units which are derived from (a) about 50 to about 80% byweight butyl acrylate, or optionally a mixture of butyl acrylate and2-ethylhexyl acrylate containing up to about 40% 2-ethylhexyl acrylate,(b) from about 3 to about 25% by weight of at least one member selectedfrom the group consisting of methyl methacrylate, ethyl methacrylate,methyl acrylate, and ethyl acrylate, (c) optionally about 0 to about 40%of an alkoxy ethyl acrylate or an alkoxy ethyl methacrylate, (d) fromabout 6 to about 30% by weight acrylonitrile, (e) from about 5 to about18% by weight styrene, (f) from about 0.5 to about 4% by weight of acrosslinking agent, and (g) from about 1% to about 8% by weight of themonomer containing reactive cure sites.
 4. A rubbery polymer asspecified in claim 1 which is comprised of repeat units which arederived from (a) from about 55 to about 75% by weight butyl acrylate, oroptionally a mixture of butyl acrylate and 2-ethylhexyl acrylatecontaining up to about 40% 2-ethylhexyl acrylate, (b) from about 5 toabout 20% by weight of at least one member selected from the groupconsisting of methyl methacrylate, ethyl methacrylate, methyl acrylate,and ethyl acrylate, (c) optionally, about 0 to about 40% of an alkoxyethyl acrylate or an alkoxy ethyl methacrylate, (d) from about 10 toabout 25% by weight acrylonitrile, (e) from about 8 to about 14% byweight styrene, (f) from about 1 to about 3% by weight of a crosslinkingagent, and (g) from about 2% to about 6% by weight of the monomercontaining reactive cure sites.
 5. A rubbery polymer as specified inclaim 1 wherein the monomer containing reactive cure sites is selectedfrom the group consisting of hydroxyethyl acrylate and hydroxyethylmethacrylate.
 6. A rubbery polymer as specified in claim 1 wherein themonomer containing reactive cure sites is selected from the groupconsisting of acrylic acid and methacrylic acid.
 7. A rubbery polymer asspecified in claim 1 wherein the monomer containing reactive cure sitesis selected from the group consisting of glucidyl methacrylate and allylglycidyl ether.
 8. A rubbery polymer as specified in claim 1 wherein themonomer containing reactive cure sites is selected from the groupconsisting of dicyclopentenyl acrylate and dicyclopentenyloxyethylmethacrylate.
 9. A leathery composition which is useful in automotiveapplications, which is comprised of (1) a thermoplastic, (2) aplasticizer, and (3) a rubbery polymer as specified in claim
 1. 10. Aleathery composition as specified in claim 9 wherein the thermoplasticresin is polyvinyl chloride.
 11. A leathery composition as specified inclaim 9 wherein the thermoplastic resin is a polyolefin.
 12. A leatherycomposition as specified in claim 11 wherein the polyolefin is highdensity polyethylene.
 13. A leathery composition as specified in claim11 wherein the polyolefin is a metallocene catalyzed polyolefin.
 14. Aprocess for preparing a rubbery polymer which can be blended withthermoplastics to make leathery compositions having good heat andultraviolet light resistance, said process comprising the steps of (1)polymerizing (a) butyl acrylate, or optionally a mixture of butylacrylate and 2-ethylhexyl acrylate containing up to about 40%2-ethylhexyl acrylate, (b) at least one member selected from the groupconsisting of methyl methacrylate, ethyl methacrylate, methyl acrylate,and ethyl acrylate, (c) optionally about 0% to about 40% of alkoxy ethylme(acrylate), (d) acrylonitrile, and (e) a crosslinking agent; whereinabout 1% to about 10% of a monomer containing reactive cure sitesselected from the group consisting of hydroxyl groups, glycidyl groups,carboxylic acid groups, and unsaturated cure sites is incorporated intothe rubbery polymer under emulsion polymerization conditions to producea seed polymer containing latex; (2) adding (a) styrene, (b) additionalacrylonitrile, and (c) additional crosslinking agent to the seed polymercontaining latex under emulsion polymerization conditions which resultin the formation of an emulsion containing the rubbery polymer, whereinno additional methyl methacrylate is added to the seed polymer latex;and (3) recovering the rubbery polymer from the emulsion containing therubbery polymer.
 15. A process as specified in claim 14 wherein thepolymerization is a free radical emulsion polymerization.
 16. A processas specified in claim 15 wherein the polymerization is conducted at atemperature which is within the range of about 10° C. to about 95° C.17. A process as specified in claim 16 wherein from about 6 parts byweight to about 22 parts by weight of the styrene, about 3 parts byweight to about 12 parts by weight of the additional acrylonitrile, andabout 0.05 parts by weight to about 1 part by weight of the crosslinkingagent are added to the seed polymer latex in step (2).
 18. A process asspecified in claim 17 wherein the crosslinking agent is 1,4-butanedioldimethacrylate.
 19. A process as specified in claim 18 wherein thepolymerization is conducted at a temperature which is within the rangeof 20° C. to 80° C.
 20. A process as specified in claim 19 wherein from10 parts by weight to 17 parts by weight of the styrene, 4 parts byweight to 8 parts by weight of the additional acrylonitrile, and 0.1parts by weight to 0.5 part by weight of the 1,4-butanedioldimethacrylate are added to the seed polymer latex in step (2).